Blood 'n guts: I love when the spatters can matter so much, as they do in two great television series.

The titles are Boardwalk Empire and The Walking Dead. Both are transgressive and provocative for their insights into the dark side of human nature. Both are brilliantly orchestrated, despite upheavals behind the scenes with one. Both are acted out by excellent ensembles. Both have second seasons debuting this week on DVD, Blu-ray and digital download.

Yet the two series could not be more different.

Boardwalk Empire: The Complete Second Season

Season two just arrived in an excellent seven-disc combo pack combining DVD, Blu-ray and digital copy. Blu-ray take up five discs which showcase the gorgeous visuals of this Roarin' Twenties gangster series. The extras are extensive.

But the DVD versions and digital copy are slapped onto two flipper discs with zero extras. Obviously, DVD gets short shrift because flipper discs can be unreliable.

The Blu-ray discs are superior. Each has extras, including character dossiers. The fifth disc contains the motherlode of bonus materials. Aside from the entertainment value of watching finicky gangster Nucky Thompson (Steve Buscemi) run his crime syndicate and muck about with the politics of Atlantic City, circa 1921, Boardwalk Empire is an educational adventure on Blu-ray.

As it did with The Complete First Season release in January, HBO Home Entertainment does a splendid job of extending our viewing experience. Along with more conventional making-of material, there is a clutch of features and informational scrolls under the umbrella title, Living in 1921. Among them is the featurette Ireland and Sinn Fein, recounting the connection between The Irish Troubles and U.S. sympathizers. Not incidentally, a history of the Tommy Gun is added. Another scroll recounts how the Ku Klux Klan resurged after D.W. Griffith's controversial 1915 film, The Birth of a Nation, portrayed the KKK as Civil War heroes.

On a micro scale, we see how clothes made the man with Buscemi's Nucky.

"I am one of the least fashion-conscious people on the Earth," Buscemi admits. But the designers went to work with enthusiasm. "He's not just a guy in a suit," says fashion expert Chris Laverty, editor of Clothes on Film. "He has his own iconography."

Combine the history and the minutiae and Boardwalk Empire is an even richer, fuller, more fascinating experience as it heads into season three.

The Walking Dead: The Complete Second Season

The sudden departure of Frank Darabont, who originally conjured this show from the popular graphic novel, created a dark cloud over season two. Regardless of whether he quit or was fired, the series changed. After a gonzo start with a horde of zombies, the survival story two slowed down to a more measured pace than Darabont had maintained in season one. There was more reflection, less action. It settled into a holding pattern revolving around a missing person plot.

Yet The Walking Dead is still a mesmerizing series that revolves around a manly hero, sheriff's deputy Rick Grimes (played by Andrew Lincoln). From the beginning, he has been the touchstone for what this zombie apocalypse story is really all about: How do people maintain their humanity in the face of extreme adversity?

Season two debuted this week in separate DVD and Blu-ray sets. I have the Blu-ray for review. As with season one, there are first-class extras. They include intimate close-ups of behind-the-scenes stuff, including seeing "the zombie maestro" in action. That would be co-executive producer Greg Nicotero, who doubles as special effects makeup designer. Seeing him stuff some gooey guts into nylon stockings to serve as a zombie's vital organs is priceless.